Chalmers Open Digital Repository
Not a member yet
26247 research outputs found
Sort by
Biobased removable textile prints - Exploration of biobased binders for the purpose of screen printing
No full textThe textile industry has a substantial environmental and climate impact. One approach to reducing this footprint is to increase the reuse and recyclability of post-consumer garments. Vividye addresses this challenge by enabling removable textile prints through a detachable priming layer beneath conventional inks. This thesis investigates the development of a biobased alternative to the currently used latex binder in the priming layer, with the goal of maintaining key performance properties such as removability, printability, and washability. Four biobased binders were explored: an emulsion of crosslinked castor oil, polylactic acid (PLA) powder, powdered ethyl cellulose, and an aqueous ethyl cellulose dispersion, commercially known as Surelease®. The most promising formulation used Surelease® as the main binder and PLA as a filler. To improve rheological behavior, a cellulose derivative was added as a thickener. Multiple formulations with varying ratios of these components were prepared and evaluated through film casting and visual inspection. Wettability was assessed using an optical goniometer. While the final formulation did not fully match the film forming and washability performance of the original latex-based system, it demonstrated comparable removability and superior printability. These results demonstrate the potential of biobased alternatives for more sustainable textile printing
Digital Fika - Designing Accessible Digital User Experiences for Older Adults
No full textThis thesis explores accessibility and digital commensality through creating a set of recommendations and developing a website prototype called Digital Fika. Through an iterative process the prototype was developed and tested with a user group consisting of older adults around the ages of 70 and 80 years. The users were a bit skeptical towards Digital Fika at first, but when the concept had a more refined and responsive prototype interface they were more interested and positive towards
it. Throughout the process, a set of recommendations for how to build an accessible web page were also created. It became clear during the process that the testers were not diverse enough to create and test a broad set of accessibility recommendations, rather they fit able bodied older adults with some experience of technology and a variation of visual impairments. To further the research in this thesis, one should test the concept and accessibility guidelines with a test group with a more varied set of impairments to give a more accurate account of which accessibility recommendations are important, and more varied in cultural background to see how that affects socialization. In addition to this, one could look at the accessibility of the technology users use to interact with the website
Modification and Validation of the Neck Soft Tissue Models in the SAFER HBM
No full textCervical spine injuries are common in motor vehicle collisions. Human body models (HBMs) are used in virtual crash simulations to estimate injury risks. The SAFER (Vehicle and Traffic Safety Center at Chalmers) HBM (SHBM) is one such model capable of simulating occupant kinematics and evaluating injury risks. Within the SAFER research initiative, the cervical spine model is being updated under the project “Improving Neck Injury Prediction in Car Crashes Using SAFER HBM.” Neck response is influenced not only by the cervical spine but also by surrounding soft tissues such as muscle, fat, and skin.
The aim of this thesis is to investigate and modify the material model and the model geometry of the SHBM neck soft tissue, then validate the biofidelity of the updated neck soft tissue model under both low and high acceleration crash scenarios. Head-neck range of motion (ROM) experiments conducted with human volunteers were replicated using SHBM, and the resulting neck responses were analyzed to understand the effect of the neck soft tissue to neck ROM. A parameter study was carried out to adjust the soft tissue parameters and achieve better agreement between the SHBM neck response and the experimental ROM data. The updated parameters obtained from the parameter study were further calibrated by simulating post-mortem human subject (PMHS) tests using the SHBM under high-acceleration loading conditions. Design modifications such as refining the neck soft tissue mesh and incorporating the nuchal ligament were subsequently implemented to enhance model biofidelity. Finally, a validation study was conducted by simulating both low- and high-speed PMHS crash tests using the original SHBM model geometry with the most promising parameter configurations.
ROM simulations revealed that the SHBM neck exhibited higher resistance to extension and axial rotation compared to experimental results. Following parameter tuning and calibration, a notable reduction in neck moments was achieved. Validation simulations using the updated parameters yielded responses that closely matched experimental reference values.
Although material updates improved neck response, further refinement particularly of the strain-rate-dependent skin model could enhance biofidelity across varying loading rates. Exploring alternative neck flesh material models and refining nuchal ligament design are also promising directions. A key limitation is that SHBM represents only 50th percentile male, limiting generalizability. Extending future investigations to account for population diversity would improve model applicability.
In conclusion, the current SHBM version (v11.1.0) exhibits neck responses under low acceleration conditions that are stiffer than reference values, and softer responses under high acceleration conditions than reference values. The calibrated material parameters resulted in response that was better aligned with experimental data. Minor influence on head forward excursion in validation simulations. The addition of the nuchal ligament improved flexion behavior and is recommended for future versions
Novel control of run-around heat recovery system: Evaluation of the novel control method’s performance through laboratory experiments
No full textRun-around coil (RAC) systems are particularly well-suited for applications requiring complete
separation between supply and exhaust airflows, such as hospitals, laboratories, and other
facilities with stringent hygiene or contamination control requirements. Unlike rotary or plate type heat exchangers, RAC systems ensure full airstream separation while offering design
flexibility and modular installation, making them appropriate for complex and specialized
ventilation scenarios. However, their efficient operation critically depends on the accurate
control of the circulating liquid flow rate to achieve optimal heat recovery performance.
Traditional control strategies regulate liquid flow based on balancing the heat capacity flow rates
of air and liquid media, which requires accurate real-time knowledge of their thermophysical
properties. This approach becomes challenging in dynamic operational environments, especially
under demand-controlled ventilation (DCV) conditions, where airflows fluctuate in response to
changing occupancy. Moreover, accurately measuring flow rates and properties in real-time
often increases system complexity, limiting the practicality of such control strategies.
To address these challenges, a novel temperature-based control method was developed and
evaluated through laboratory experiments. This new approach relies on temperature
measurements, rather than flow measurements or thermophysical property estimations, to
regulate the system. The method aims to enhance system adaptability, reduce measurement
uncertainties, and maintain stable heat recovery performance across a wide range of ventilation
demands and external conditions. The experimental evaluation focused on testing this strategy's
effectiveness, robustness, and responsiveness compared to conventional flow-based control
methods.
The results demonstrate that the temperature-based control method (Xt) offers a reliable and
efficient alternative, particularly in applications where fluid properties are variable or where
accurate flow sensors are impractical. With appropriate tuning of control parameters,
specifically the proportional and integral settings, the method achieved consistently high
effectiveness and system stability across variable conditions. The findings suggest strong
potential for integrating this novel control approach into both new and existing RAC
installations, supporting improved energy efficiency and simplified operation in real-world DCV
systems
A quiet language: Translating vernacular architecture for future needs
No full textWith the continued development of universal tools
and construction techniques, one could argue that
architecture more and more tends to become a
consumer product. Previously, towns had distinctive
regional and cultural characteristics which was a
result of peoples direct understanding of the place
they inhabited, something that has tended to be lost
the further one goes into modern society. Critical
regionalism, with the architect Kenneth Frampton in the
forefront, advocated for an alternative approach. As to
instead negotiate architectural progress through the
peculiarities of a specific place. Which highlights the
architects need for sensitivity to the existing conditions
of the place.
The thesis in turn adopts a design method that aims
to explore the translation of vernacular architecture,
in order to approach critical regionalism and explore
its spectrum of embeddedness and contemporaneity,
when dealing with new construction. Sikhall, a
rural area in Dalsland, acts as the test bed for
these explorations. It has had a long history of both
prosperity and hardship and has thus cemented
itself as a significant place in the local region. The
design method builds upon literary studies, site
visits, drawings, collages, digital reconstructions and
design explorations through translation. The digital
reconstructions summarized the survey regarding the
vernacular architecture which acted as the base for the
analysis before the translations could take place.
The result is a proposal for a revitalized area with a
new program building upon Sikhalls historical context,
as well as the addition of a new flexible communal
building. Deriving from the translations of the local
vernacular architecture. Containing a café and
exhibition space.
The open ended method of translation presents many
opportunities depending on the interpretations of the
translator. And puts the relation between the copy
and the original at the forefront, as a project could
lean towards one side or the other depending on the
context. The discussion whether there is an optimal
position on the embeddedness and contemporaneity
scale highlights the complexity of the method, as well
as the needed sensitivity towards the context of every
project. As it is in the translation that new compositions
could be discovered
Electrochemical investigation of Fe- and Zr-based alloys in standard conditions and under gamma irradiation in contact with H2O2
No full textRadiation induced corrosion is a major problem for the longevity of nuclear power plants,
and the research into this field is hampered by the requirement to accurately simulate
reactor conditions in experiments. This study attempts to electrochemically investigate
the interaction between hydrogen peroxide (H2O2) and the alloys AISI 441 and Zircalloy-2
(Zry2), both under standard conditions and under γ irradiation.
The results from the linear scan voltammetry (LSV) indicate that the anodic oxidation
reaction between AISI 441 and H2O2 might be catalyzed by γ irradiation. Whereas the
cathodic reduction reaction may be inhibited by the radiation. With regards to Zry2 the
anodic LSV results show a possible surface area limitation on the reaction. The cathodic
experiments highlight the chemical inertness that the alloy is known for, though there
appears to be a inhibitory effect of γ radiation upon the evolution of hydrogen.
These findings highlight the greater sensitivity of AISI 441 to radioactive environments,
which may have implications for material selection in reactor design
CO mpis – A Tool for CO Reduction in Fit-Outs: Wireframe-development of the communication tool CO mpis
No full textThe building and construction sector is responsible for a large share of global carbon emissions and extraction of material resources. Within the construction sector, one significant contributor is fit-outs. A fit-out is the process when a commercial space is customized to meet tenant needs. Fit-outs are done frequently from a lifecycle perspective, consequently leading to large amounts of carbon emissions.
The aim of this thesis is to facilitate the reduction of CO₂ emissions in fit-outs. The thesis is designed to apply to the real estate company Vasakronan and is conducted in a Swedish context. To realize the aim, Circular economy (CE) was applied to facilitate sustainability in fit-outs. However, implementation of circular economy into fit-out projects is a complex process. Fit-outs are multifaced and tenants' opinions and wishes can become hinders. To enable CEs implementation, efficient communication between real estate owners and tenants is crucial. This thesis seeks to overcome the communication gap, by creating a communication tool for material selection named “CO₂mpis”. Interviews with actors at Vasakronan were held to identify their needs in a communication tool. The needs were specified using user stories. Based on these, a wireframe was developed using insights from a market scan, hotspot analysis and development of a CE framework. The findings were used to create the functionalities included in the wireframe. This includes compering materials carbon emissions, visualizing differences (e.g., reused vs. new materials), and expressing them in relatable terms, such as numbers of plane trips. The tool also enables comparison of different projects and suggests circular strategies for materials. The results show how the gap in communication can be overcome by implementing CO₂mpis
